TOPTICA Photonics AG offers a wide range of optical fibers ideally suited for use with TOPTICAs lasers and FiberDock. These economically priced fibers cover a wide range of wavelengths. TOPTICA recommends to always purchase a fiber along with a laser and fiber coupler, as this ensures maximum fiber coupling efficiency. Also specialty fibers for power monitoring, beam splitting or combining are available with various ratios and also polarization maintaining. Please enquire.

TOPTICAs laser systems generally produce light that is diffraction limited or at least nearly so. It can therefore be coupled efficiently into single-mode fibers. Coupling single-mode light into a multi-mode (MM) fiber will result in a loss of brightness, although the coupling efficiency might be better and the coupling is less sensitive to misalignment – the output of the MM fiber will generally be multi-mode. To preserve the favorable properties of single-mode light, it should be coupled into single-mode (SM) fibers.

Coupling polarized light into a single-mode fiber will result in random polarization at the output of the fiber, because the fiber is generally slightly birefringent. As this birefringence changes with temperature and movement/bending of the fiber, also the output polarization of a SM fiber varies.

Polarization maintaining (PM) fibers can preserve the input polarization under certain circumstances. In PM fibers, a strong birefringence is introduced intentionally in a controlled way, and coupling linearly polarized light into a PM fiber along one of its principal axes will maintain the polarization. The polarization crosstalk from one axis to the other is generally smaller than -25 dB/100 m, for wavelengths below 480 nm smaller than -20 dB/100 m. The key of PM fibers is mostly aligned along the slow axis, and this is normally the axis along which the polarization is coupled into the fiber. TOPTICAs fiber coupler FiberDock offers a degree of freedom to rotate the fiber around its axis to optimize this alignment.

Normally, every fiber facet introduces 4% loss, reducing the theoretical maximum transmission through a fiber to 92%. Anti-reflection coated (AR) fibers reduce these reflection losses to below 1%, so that the power behind the fiber can be increased by 6-8%. The AR coating withstands high powers, but is not suited for physical contact (PC) fiber-to-fiber coupling. AR coated fibers are available at many wavelengths upon request.

High power (HP) fibers are recommended for powers greater than 1000 mW in the infrared, and 100 mW in the visible. The output beam from high power fibers shows very little distortion with M² << 1.1.